[build_system] Use an absolute path for the inclusion of makefile.gnu.config
[build_system] Use an absolute path for the inclusion of makefile.gnu.config

mit-carbon/Graphite,victorisildur/Graphite,mit-carbon/Graphite,victorisildur/Graphite,fhijaz/Graphite,victorisildur/Graphite,fhijaz/Graphite,nkawahara/Graphite,8l/Graphite,8l/Graphite,nkawahara/Graphite,fhijaz/Graphite,mit-carbon/Graphite,nkawahara/Graphite,mit-carbon/Graphite-Cycle-Level,8l/Graphite,victorisildur/Graphite,fhijaz/Graphite,mit-carbon/Graphite-Cycle-Level,mit-carbon/Graphite-Cycle-Level,8l/Graphite,mit-carbon/Graphite-Cycle-Level,mit-carbon/Graphite,nkawahara/Graphite